The present disclosure relates to respiratory condition analysis apparatuses, and, more particularly, to a respiratory condition analysis apparatus and a respiratory condition display apparatus which analyze the respiratory condition of a living body such as a human being on the basis of a time-series respiratory signal including respiratory sound of the human being, a processing method therein, and a program for causing a computer to execute the method.
Monitoring of respiratory sound using a stethoscope or the like has been widely performed to check a biological condition. A respiratory condition analysis apparatus for analyzing a respiratory condition on the basis of a time-series respiratory signal including respiratory sound monitored by a stethoscope or the like has been developed.
For example, an apparatus for calculating spectrum information by performing Fast Fourier Transform (FFT) processing on respiratory sound data in each of a plurality of time segments having different lengths set in advance, and detecting abnormal sound by analyzing the spectrum information has been proposed (see, for example, Japanese Unexamined Patent Application Publication No. 2005-066045). In this related art, abnormal sound is detected by determining whether a dominant frequency component (formant) defining the type of abnormal sound has lasted for a predetermined period on the basis of a spectral envelope on a sound spectrogram and the sound spectrogram. For example, when a high-frequency component (500 Hz to 1000 Hz) lasts for a period equal to or shorter than 25 milliseconds at an intensity equal to or greater than a predetermined intensity, it is determined that the high-frequency component is generated by a discontinuous rale. When a frequency equal to or higher than 400 Hz lasts for a period equal to or longer than 250 milliseconds at an intensity equal to or greater than a predetermined intensity, it is determined that the frequency is generated by a continuous rale. Each of the discontinuous rale and the continuous rale is adventitious sound included in respiratory sound, and is determined to be abnormal sound.